The present invention relates to an image exposure apparatus, and in particular, to an image exposure apparatus that exposes photosensitive materials by using rays of light each having a different wavelength emitted from a plurality of light-emitting elements.
In recent years, there has been proposed to be put to practical use an image exposure apparatus that is equipped with array light sources each being composed of a plurality of light-emitting elements for each recording color. FIG. 9 is an illustration showing how exposure is carried out in the conventional image exposure apparatus. This image exposure apparatus is equipped with three array light sources 210, 220 and 230 each having substantially the same width as in photographic paper 100, for exposing the photographic paper 100 to light.
Each of these three array light sources 210, 220 and 230 emits light in accordance with each of R, G and B recording colors. When photographic paper 100 is conveyed in the direction of an arrow in the drawing, each of the array light sources 210, 220 and 230 was driven by staggering timing in accordance with the conveyance speed of the photographic paper 100 so that exposures for R, G and B may be conducted on the same position on the photographic paper 100.
When driving each of the array light sources 210, 220 and 230 by staggering the timing in accordance with the conveyance speed of the photographic paper 100, it is necessary to stagger the timing of driving signals to be supplied to each array light source in accordance with the conveyance speed. Therefore, there has been a problem that the structure of a driving circuit and control of the timing are complicated. Further, if the conveyance speed fails to be constant during the period from completion of exposure of a certain recording color to exposure of another color for the same pixel, there is caused a problem of out of color registration. For preventing the out of color registration, therefore, it was necessary to control strictly the conveyance speed for photographic paper 100.
To solve the problems stated above, there has been suggested a method to mix array-shaped emergent light emitted from each array light source, by using a light-mixing member such as dichroic prism 300 equipped with a light selective film that transmits or reflects light selectively depending on a wavelength. FIG. 10 is a schematic diagram showing how the dichroic prism 300 mixes light.
The dichroic prism 300 is composed of first transparent member 310, second transparent member 320 and third transparent member 330 which are made of optical glass. Between the first transparent member 310 and the second transparent member 320, there is provided first light selective film 340 that transmits or reflects selectively depending on a wavelength of light. In the same way, there is provided second light selective film 350 that transmits or reflects selectively depending on a wavelength of light, between the second transparent member 320 and the third transparent member 330.
When the dichroic prism 300 of this kind is used, linear emergent light emitted from array light source 210 is transmitted successively through the first transparent member 310, the first light selective film 340, the second transparent member 320, the second light selective film 350 and the third transparent member 330, and emerges. On the other hand, linear emergent light emitted from array light source 220 is transmitted through the second transparent member 320 and is reflected on the first light selective film 340, then, is transmitted successively through the second light selective film 350 and the third transparent member 330, and emerges. Further, linear emergent light emitted from array light source 230 is transmitted through the third transparent member 330 and is reflected on the second light selective film 350, to emerge. Through the paths mentioned above, each linear emergent light emitted from each of array light sources 210, 220 and 230 is tied up in a line.
An ordinary method to be employed for providing light selective films 340 and 350 on the dichroic prism 300 of this kind is one to deposit a metal such as aluminum or silver on a transparent member. However, each of transparent members 310, 320 and 330 constituting the dichroic prism 300 is a relatively long member matching with a line length of the array light source, and xe2x80x9ca warpxe2x80x9d is frequently caused in the longitudinal direction by heating in the course of deposition accordingly. When these transparent members each having xe2x80x9ca warpxe2x80x9d were jointed with each other, bubbles were generated between both transparent members or xe2x80x9ca warpxe2x80x9d was generated on the total product in some cases to deteriorate quality.
In the conventional dichroic prism 300, there was provided composition plane 360 having a relatively large area, as shown in FIG. 10, in addition to the composition plane forming the first light selective film 340 and the second light selective film 350, thus, an area of the total composition planes was great. When an area of the total composition planes is great, the possibility for both xe2x80x9cwarpedxe2x80x9d portions of the transparent members to come into contact with each other is great, thus, the problem of the quality deterioration has tended to happen.
Next, the first light selective film 340 and the second light selective film 350 both provided on the dichroic prism 300 have characteristics to transmit or reflect selectively depending on a wavelength of light as stated above. In general, when the light selective films have the characteristics of this kind, each of them needs to have a complicated layer structure having a certain extent of thickness.
However, each of the first light selective film 340 and the second light selective film 350 is provided at the portion sandwiched by the transparent members, and therefore, it is difficult for each of them to have the complicated layer structure having a sufficient thickness. For this reason, it is sometimes impossible to demonstrate sufficient transmission/reflection characteristics.
For example, when P polarized light and S polarized light are mixed in emergent light emitted from an array light source, a difference tends to be caused on a wavelength for the P polarized light in the case of switching from transmission to reflection and on a wavelength for the S polarized light in the case of switching from transmission to reflection, and if this difference is caused, the P polarized light and the S polarized light are averaged, and the intermediate state between transmission and reflection (half-transmitting and half-reflecting) is caused. As a result, efficiency of using light is sometimes lowered.
In this case, if a wavelength of P polarized light in the case of switching from transmission to reflection and a wavelength of S polarized light in the case of switching from transmission to reflection can be made to be close each other, it is possible to solve the aforesaid problem that efficiency of using light is lowered. However, for this purpose, the light selective film needs to be thick, and it has been difficult to construct a thick light selective film on the portion sandwiched by transparent members.
To overcome the abovementioned drawbacks, it is a first object of the present invention to provide a high-quality light-mixing part (hereinafter, also referred to as an optical device) having little warp in its longitudinal direction, and an image-exposing apparatus provided with the abovementioned light-mixing part and an image-exposing method employing the abovementioned light-mixing part.
Further, it is a second object of the present invention that, in an image-exposing apparatus which mixes a plurality of lights having wavelengths different relative to each other and emitted from a plurality of light-emitting elements to expose a photosensitive material, deterioration of the working efficiencies of these emitted lights are prevented, even in case that the polarizing surfaces of the lights, emitted from the light-emitting elements, do not coincide with each other in a unified direction.
Accordingly, to overcome the cited shortcomings, the abovementioned object of the present invention can be attained by optical devices, image-exposing apparatus and image-exposing methods described as follow.
(1) An optical device, which mixes a plurality of lights coming from directions being different relative to each other, so as to emit a mixed light in a unilateral direction, the optical device comprising: a first transparent member to receive a first light emitted from a first light-emitting element row; a second transparent member to receive a second light emitted from a second light-emitting element row; a third transparent member to receive a third light emitted from a third light-emitting element row; a first composition plane, at which the first transparent member and the second transparent member are jointed together and a first light selective film is formed, the first light and the third light penetrating through the first light selective film while the second light being reflected by the first light selective film toward a traveling direction same as that of the first light and the third light; a second composition plane, at which the first transparent member and the third transparent member are jointed together and a second light selective film is formed, the third light penetrating through the second light selective film while the first light being reflected by the second light selective film toward the traveling direction same as that of the third light; and a wavelength controlling element to exclude a wavelength region of the first light from a differential region between a wavelength at which a P-polarization changes from transmission to reflection in the first composition plane and another wavelength at which a S-polarization changes from transmission to reflection in the first composition plane.
(2) The optical device of item 1, wherein the wavelength controlling element is provided on the first transparent member in an exposed state, and is a third light selective film through which the first light penetrates in a wavelength selective manner.
(3) The optical device of item 1, wherein the first light is a blue light, the second light is a green light and the third light is a red light.
(4) An optical device, which mixes a plurality of lights coming from directions being different relative to each other, so as to emit a mixed light in a unilateral direction, the optical device comprising: a first transparent member, having an angular portion, to receive a first light emitted from a first light-emitting element row; a second transparent member to receive a second light emitted from a second light-emitting element row; a third transparent member to receive a third light emitted from a third light-emitting element row; a first composition plane, at which the first transparent member and the second transparent member are jointed together and a first light selective film is formed, the first light and the third light penetrating through the first light selective film while the second light being reflected by the first light selective film toward a traveling direction same as that of the first light and the third light; a second composition plane, at which the first transparent member and the third transparent member are jointed together and a second light selective film is formed, the third light penetrating through the second light selective film while the first light being reflected by the second light selective film toward the traveling direction same as that of the third light; and a third composition plane, which resides on an extended line of the first composition plane, and at which the second transparent member and the third transparent member are jointed together; wherein the angular portion of the first transparent member is fitted into a concave portion formed by the second composition plane and the third composition plane.
(5) The optical device of item 4, wherein a shape of the first transparent member is a lengthy pentagonal column, a top portion of which is an intersection of the first composition plane and the second composition plane, a shape of the second transparent member is a lengthy square column, in which the second composition plane and the third composition plane constitute a continuously-sloped surface, and a shape of the third transparent member is a lengthy triangle column having the angular portion, which is fitted into the concave portion formed by the second composition plane and the third composition plane.
(6) The optical device of item 4, wherein, when a total area of a side surface, including the third composition plane, of the third transparent member is defined as S1, and an area of the third composition plane is defined as S2, the following equation is established.
S2 less than (xc2xd)S1
(7) The optical device of item 4, wherein end portions of the second composition plane and the third composition plane are disposed outside an aperture angle region of a light-conversing element equipped in a direction of emitting the mixed light, the end portions being located at farther position with respect to the light-conversing element.
(8) An apparatus for exposing an image onto a photosensitive material, the apparatus comprising: a first light-emitting element row to emit a first light; a second light-emitting element row to emit a second light in a direction different from that of emitting the first light; a third light-emitting element row to emit a third light in a direction different from those of emitting the first light and the second light; an optical device to mix the first light, the second light and the third light, which come from directions being different relative to each other, so as to emit a mixed light in a unilateral direction, the mixed light being distributed on a line to expose the photosensitive material; and a moving device to move either the photosensitive material or the optical device in a direction substantially orthogonal to the line of the mixed light; wherein the optical device comprises: a first transparent member, having an angular portion, to receive the first light; a second transparent member to receive the second light; a third transparent member to receive the third light; a first composition plane, at which the first transparent member and the second transparent member are jointed together and a first light selective film is formed, the first light and the third light penetrating through the first light selective film while the second light being reflected by the first light selective film toward a traveling direction same as that of the first light and the third light; a second composition plane, at which the first transparent member and the third transparent member are jointed together and a second light selective film is formed, the third light penetrating through the second light selective film while the first light being reflected by the second light selective film toward the traveling direction same as that of the third light; and a third composition plane, which resides on an extended line of the first composition plane, and at which the second transparent member and the third transparent member are jointed together; wherein the angular portion of the first transparent member is fitted into a concave portion formed by the second composition plane and the third composition plane.
(9) The apparatus of item 8, wherein a shape of the first transparent member is a lengthy pentagonal column, a top portion of which is an intersection of the first composition plane and the second composition plane, a shape of the second transparent member is a lengthy square column, in which the second composition plane and the third composition plane constitute a continuously-sloped surface, and a shape of the third transparent member is a lengthy triangle column having the angular portion, which is fitted into the concave portion formed by the second composition plane and the third composition plane.
(10) The apparatus of item 8, wherein the first light is a blue light, the second light is a green light and the third light is a red light.
(11) A method for exposing an image onto a photosensitive material, the method comprising the steps of: emitting a first light, a second light and a third light, directions of which are different relative to each other, toward an optical device; mixing the first light, the second light and the third light, both entering the optical device, with each other in the optical device; exposing a mixed light onto the photosensitive material, the mixed light being distributed on a line; and moving either the photosensitive material or the optical device in a direction substantially orthogonal to the line of the mixed light; wherein the optical device comprises: a first transparent member, having an angular portion, to receive the first light; a second transparent member to receive the second light; a third transparent member to receive the third light; a first composition plane, at which the first transparent member and the second transparent member are jointed together and a first light selective film is formed, the first light and the third light penetrating through the first light selective film while the second light being reflected by the first light selective film toward a traveling direction same as that of the first light and the third light; a second composition plane, at which the first transparent member and the third transparent member are jointed together and a second light selective film is formed, the third light penetrating through the second light selective film while the first light being reflected by the second light selective film toward the traveling direction same as that of the third light; and a third composition plane, which resides on an extended line of the first composition plane, and at which the second transparent member and the third transparent member are jointed together; wherein the angular portion of the first transparent member is fitted into a concave portion formed by the second composition plane and the third composition plane.
(12) The optical device of item 4, wherein a non-polished surface is provided at a surface other than a light-receiving surface of the third transparent member which receives the third light and a surface which forms the second composition plane.
(13) The optical device of item 4, wherein a non-polished surface is provided at a surface other than a light-receiving surface of the first transparent member which receives the first light and a surface which forms the first composition plane.
(14) The optical device of item 4, wherein a non-polished surface is provided at a surface other than a light-receiving surface of the second transparent member which receives the second light and a surface which forms the second composition plane.
(15) An optical device, which is constituted by joining three transparent members with each other and mixes lights coming from three directions being different relative to each other, so as to emit a mixed light in a unilateral direction, the optical device comprising: light-entering surfaces each of which provided on each of the three transparent members and receives each of the lights coming from the three directions; and composition planes to transmit or reflect the lights coming from the three directions so as to emit the mixed light in the unilateral direction; wherein, in each of the three transparent members, a surface, other than each of the light-entering surfaces and each of the composition planes, is a non-polished surface.
(16) An apparatus for exposing an image onto a photosensitive material, the apparatus comprising: a first light-emitting element row to emit a first light; a second light-emitting element row to emit a second light in a direction being different from that of the first light; a third light-emitting element row to emit a third light in a direction being different from those of the first light and the second light; an optical device, which is constituted by joining three transparent members with each other and mixes the first light, the second light and the third light, those coming from directions being different relative to each other, so as to emit a mixed light in a unilateral direction, the mixed light being distributed on a line to expose the photosensitive material; and a moving device to move either the photosensitive material or the optical device in a direction substantially orthogonal to the line of the mixed light; wherein the optical device comprises: light-entering surfaces each of which provided on each of the three transparent members and receives each of the lights coming from the three directions; and composition planes to transmit or reflect the lights coming from the three directions so as to emit the mixed light in the unilateral direction; and wherein, in each of the three transparent members, a surface, other than each of the light-entering surfaces and each of the composition planes, is a non-polished surface.
Further, to overcome the abovementioned problems, other optical devices, image-exposing apparatus and image-exposing methods, embodied in the present invention, will be described as follow:
(17) A light-mixing part, characterized in that,
in the light-mixing part, which is structured by joining side surfaces of first, second and third transparent members, each shaped in a lengthy pentagonal column, to form a line-type emission light by mixing lights having wavelengths different relative to each other and emitted from first, second and third light-emitting elements,
a first composition plane is formed by joining one side surface of the first transparent member and one side surface of the second transparent member together, and a concave portion, into which one angular portion of the third transparent member is fitted, is formed by another surface of the second composition plane and a part of said one side surface of the second composition plane, and a first light selective film, which selectively transmits or reflects the light corresponding to its wavelength, is formed on the first composition plane, and a second composition plane is formed by joining the other side surface of the first transparent member and one side surface of the second transparent member together in a state of fitting one angular portion of the third transparent member into the concave portion, and a second light selective film, which selectively transmits or reflects the light corresponding to its wavelength, is formed on the second composition plane, and a third composition plane is formed by joining one side surface of the second transparent member and a part of another side surface of the third transparent member together, and a first light emitted from the first light-emitting element, a second light emitted from the second light-emitting element and a third light emitted from the third light-emitting element are received by the first transparent member, the second transparent member and the third transparent member, respectively, and the second light selective film makes the third light transmitting through it toward the first transparent member side and makes the first light reflecting on it toward the direction same as that of the third light, and then, the first light selective film makes the first light and the third light transmitting through it to emit them toward the second transparent member and makes the second light reflecting on it toward the direction same as that of the first light and the third light.
(18) The light-mixing part, described in item 17, characterized in that,
when a total area of the other side of the third transparent member is defined as S1, and a partial area where the third composition plane is formed among the other side of the third transparent member is defined as S2, the relationship of
S2 less than (xc2xd)S1
is fulfilled.
(19) The light-mixing part, described in item 17 or item 18, characterized in that,
when a light-conversing means is equipped in a direction of emitting the mixed light, end portions of the second composition plane and the third composition plane, which are located at farther positions in respect to the light-conversing means, are disposed outside an aperture angle region of the light-conversing element.
(20) An image-exposing apparatus, characterized in that,
in the image-exposing apparatus, which exposes an image onto a photosensitive material by employing lights emitted from first, second and third light-emitting element rows,
the light-mixing part, described anyone of items 1-3, which forms a line-type emission light by mixing lights having wavelengths different relative to each other and emitted from the first, second and third light-emitting elements,
moving means for moving at least one of the photosensitive material and the light-mixing part, so that a exposed line, formed by exposing the line-type emission light onto the photosensitive material, is moved in a direction substantially orthogonal to the exposed line,
are provided.
(21) An image-exposing method, characterized in that,
in the image-exposing method for exposing an image onto a photosensitive material by employing lights emitted from first, second and third light-emitting element rows,
a light-mixing process for forming a line-type emission light by mixing lights having wavelengths different relative to each other and emitted from the first, second and third light-emitting elements by means of the light-mixing part described anyone of items 1-3
a moving-exposure process for exposing the line-type emission light onto the photosensitive material, while moving at least one of the photosensitive material and the light-mixing part, so that a exposed line, formed by exposing the line-type emission light onto the photosensitive material, is moved in a direction substantially orthogonal to the exposed line,
are provided.
(22) An image-exposing apparatus, characterized in that,
in the image-exposing apparatus, which exposes an image onto a photosensitive material by employing first, second and third lights emitted from first, second and third light-emitting element rows,
the light-mixing part, which forms a line-type emission light by mixing the first, second and third lights, and
moving means for moving at least one of the photosensitive material and the light-mixing part, so that a exposed line, formed by exposing the line-type emission light onto the photosensitive material, is moved in a direction substantially orthogonal to the exposed line,
are provided, and
the light-mixing part is formed by joining the three transparent members, each of which receives each of the first, second and third lights, and
each of the transparent members provided with a first composition plane and a second composition plane, on which first and second light selective films, for emitting the first, second and third lights in a unilateral direction by transmitting or reflecting each of them, are formed, and the first light selective film transmits the first light while reflects the second light in a direction same as that of the transmitted first light, and the second light selective film transmits the first light and the second light while reflects the third light in a direction same as that of the transmitted first and second lights, and wavelength controlling means, for excluding a wavelength region of said second light from a differential region between a wavelength at which a P-polarization changes from transmission to reflection in said second composition plane and another wavelength at which a S-polarization changes from transmission to reflection in said second composition plane, is provided.
(23) The image-exposing apparatus of item 22, characterized in that,
the wavelength controlling means is a third light selective film, which is equipped on the surface of the second transparent member in an exposed state and from which the second light, emitted from the second light-emitting element row, enters.